With the development of a mobile communication technology, it is imperative to achieve the purpose of a 5 Generation (5G) mobile communication technology. The 5G technology involves mobile data traffic increase for 1000 times per region, throughput increase for 10 to 100 times per user, increase of number of connecting devices for 10 to 100 times, prolonging of battery life of a low-power device for 10 times and decrease of an end-to-end delay for 5 times, so some new radio technology solutions must be proposed in 5G. Herein, Ultra-Dense Networks (UDNs) are important means for achieving first two indexes of 5G. A key technology for the UDNs is to enable a great number of points to effectively co-exist within a dense range in a homogeneous or heterogeneous manner. In order to solve the problem of frequent switching of User Equipments (UEs) under an UDN scenario, in the conventional art, a solution for a virtual cell is proposed in a 5G research, a construction mode for the virtual cell being divided into a centralized mode and a distributed mode. Under a working pattern of the virtual cell, services of the UE may be borne on different TPs in the virtual cell at different periods of time. Different data packets borne by the same virtual cell may be transmitted over different TPs in the virtual cell respectively, and the data packets need to be encrypted at an air interface. However, the encryption complexity of the UE is higher, and in order to reduce the implementation complexity of the UE end and avoid from simultaneous maintenance of a plurality of sets of key security contexts at the UE end, keys used by different TPs in the virtual cell need to be unified. Therefore, the problem about key updating of different TPs in a virtual cell under an UDN scenario needs to be solved urgently.
At present, any effective solution has not been proposed yet for the problem in the conventional art about key updating of different TPs in the virtual cell under the UDN scenario.